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"CENTER BOARDPOR VBSSELS. No. 292,890. Patented Peb. `5, 1884.v

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BY ATTORNEY y llllllllllllGl n. Perma pmu-ummm, wnhmgwn. n, c

WITNESSES wm UNTTED STATESf NPATENT muon, p

JOHN s. einen, OF New YORK, N. Y.

CENTER-BOARD FOR vEssELs..

SPECIFICATION forming part of Letters Patent No. 292,890, dated February 5, 1884.

Application filed December :29, 1382. (Nonniodel.)

To @ZZ wil/0772, it may concern:

Beit known that I, JOHN S. BIRCH, a citizen of the United States, residing at New York city, in the county and State of New York, have invented new and useful Improvements in Center-Board Vessels, of which the following is a specification.

In this improvement in center-board vessels it is designed to use a center-board having more of the form and qualities of a keel by reason of greater length and less depth than the common center-boards; and theinvention consists'of an arrangement of inclined ways for its support, and on which itl may `be raised and lowered, so that while it is made to rise andfall about in the same measure throughout its whole length, instead of swinging, as most center-boards do, the power to raise it needs only to equal about half the weight of the board, and the resistance is no more in any part of its rise than another, so that the power that is competent for moving it in any part of its course is sufficient for all parts.

In order that the center-board may project to a greater extent aft than forward, whether partly or wholly down, and that such greater extension shall be proportionately the same, whether the center-board be wholly or partly down, the ways on which the center-board rises and falls are varied as to their `inclination, the angles of the forward ways being less than those aftthat is to say7 if it be desired that the extension of the keel be three feet aft and two feet six inches forward when wholly down, the inclines shall so vary in the angles that when half down the aft end will extend one foot six inches, and the forward end one foot three inches, and so on. rlhe essential object of this arrangement is that weight applied to the lower edge ofthe center-board for ballast shall bear the same relations to the line of the center of gravity of the vessel (which rises from stern to bow) from end to end of the center-board,whetherit is wholly or partly extended.

Figure l is a longitudinal section of the hull of the vessel along the center-board space, showing my improved arrangement of the center-board, the said board being partly lowered to the bottom of itsrange. Fig. 2 is a similar view, showing the center-board lowered at the Fig. 4 is a detail in' section on the line y y, Fig. l, and 5 is a partial longitudinal, section, showing the application of a signal apparatus, as I propose to indicate the -rise of the center-board by riding on shoal bottom.

I propose to make a center-board space, a.,

along the vessel nearly from stem to stern, inclosed by two partitions, I), cover c, and the end sections, d, said space opening through the bottom of the vessel, the two sides of which are to be connected across said space at suitable intervals along it by strong bolts d', passing through the timbers c, in which they are fastened by screw-threads j', shoulder g,.and nuts 71., or equivalent devices, so as to stay the sides of the hull properly for substantial construction, and in this space I propose to al range a center-board, fi, having slots j, through which the stay-bolts d pass, the said` slots allowing the center-board to be shifted up and down, as is required for such boards; but the bolts may be omitted in small vessels.

For the means of shifting the center-board up and down, I propose to incline the slots j forty-ve degrees, or thereabout, to support about half the weight of the center-board on the bolts, so that by pulling the board backward with power equa-l to about half the weight of the center-board it will be raised up flush with the bottom of the vessel, or thereabout, and by releasing it it will slide forward and downward. A chain, Z, pulley m, and lever n, or any equivalent device, may be used for raising the board, and a latch and notched quadrant or other device may be employed for holding it up. The center-board will be sufficiently shorter than the space a to allow of the lengthwise motion ofthe said board for so raising and lowering it. I also propose to make slots o in ,the center-board for all the stay-bolts d in advance of the hinderinost one, and connect a chain, p, withthe forward end, to raise it on the sternmost bolt as a pivot, to facilitate the swinging ofthe bow around in making the tacks. g

In order to prevent undue pressure on the IOC) stermnost bolt, d', by the overbalancing forward end of the center-board when in the lowtate the working of the keel-board on them.

It will be seen that a center-board arranged on the stay-bolts d by inclined slots, as I propose, will naturally rise and relieve the vessel of undue strains when it touches bottom, if hard, and I propose to attach a signalbell, t, to be actuated by a rack, u, or any approved means, for giving warning at once of the danger at hand.

It will-be seen that my improved contrivance affords a practicalkeel, with the ad vantage of the center-board arrangement, and it is a center-board withoutmaterially greater draft than the ordinary keel, and the rise in the vessel is much less than the ordinary board rises. It is also much less subject to damage than the ordinary center-board.

In small vessels the partitions b, inclosing the center-board space, may be utilized for supporting seats x for passengers and crew.

I propose to vary the inclinations of the slots j proportionally to the required greater eX- tension ofthe center-board at the stern than at the bow-that is, the angle of the rear slot will be greatest and those forward will be less-so that for a given lengthwise movement rof the board it will rise and fall as much more at the stern end than at the bow end as the difference in the desired projection ofthe board below the bottom from end to end, whereby, it will be seen, the keel will bear the same proportionate relations to the vessel, no matter how much or little it may be let down, so that the weights attached to the lower edge for ballast will not be changed relatively to the vessel, eXcept in the degree ofthe extension ofthe keel and a slight change lengthwise, which is a material advantage as compared with those center-boards that swing up and down on one end.

I desire it to be lunderstood that I do not limit myself to the slotted arrangement of the keel-board for causing it to rise and fall, for it may have rollers or studs attached to the sides and working on inclined ways attached to or formed in the sides of partitions b. These I consider as equivalent to the slots working on the bolts d, and I mean to include them as my invention, to be used either when the staybolts are or are not used.

Having thus described my invention, what I claim, and desire to secure by Letters Patent, 1s-

1. A center-board arranged, substantially as hereinbefore set forth, on two or more inclined ways, for being raised and lowered thereon, said ways being arranged in the center-board trunk, and ranging fore and aft of the ship on about forty-ve degrees of inclination, for supporting about half the weight of the center-board while being raised and lowered, in combination with a cord or chain connected to said center-board and stretched upward in about the same inclination as said ways, for raising and lowering said centerboard by pulling about half the weight of the board, substantially as described.

2. A center-board arranged, substantially as hereinbefore set forth, on two or more inclined ways, for being raised and lowered, said ways being suitably inclined for supporting about half the weight of the board throughout the range of its travel, the aft ways having greater inclination than the forward ways, and being varied with relation to said forward ways, vto cause the center-board to extend more aft than forward, and also to cause the said greater extension to be proportionately the same for any extension of said center-board, substantially as described.

3. A center-board arranged on two or more inclined ways or" about forty five degrees, whereon about half its weight is supported, and being provided with curved ways or slots o, intersecting the inclined ways that are forward of the sternmost way, to allow the center-board to be swung up at the forward end on the sternmost way, whereon it rests as a pivot, substantially as described.

4. In a center-board arranged on two or more inclined ways of Iabout forty-five degrees, whereon about half its weight is supported, the rollers q and ways t, in combination with the center-board, and located at one end of the center-board, to resist the thrust of the overh balance of the other end when the board shifts along said inclined ways, substantially as described.

In witness whereof I have hereunto signed my name in the presence of two subscribing witnesses.

JOHN S. BIRCH.

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